High-grade plasmacytoma refers to high-grade plasmacytoma of the ovary. Like other types of ovarian cancer, it is divided into stages I-IV. Stage I is mainly when the tumor is confined to the ovary. Stage I is mainly when the tumor is confined to one or both ovaries, but has spread to the pelvis. Continuing to stage III, it means that the tumor involves one or both ovaries and also confirms the presence of extra-pelvic peritoneal metastasis or pelvic lymph node metastasis, in which case there is a large amount of malignant ascites. The disease continues to progress to stage IV, in which case distant metastases have developed, and such distant metastases do not include peritoneal metastases, which are only stage III. There are distant organs, such as lungs or liver, and metastases like these enter a most advanced stage. It is important to emphasize here that high-grade plasmacytoma is only a qualitative classification of ovarian cancer pathology, in which high-grade refers to tumors that are more malignant and very poorly differentiated. Plasmacytoma is a characteristic of ovarian epithelial deterioration and is only qualitative. Staging has nothing to do with this characterization, but is based on the degree of its growth and spread.